Contact assembly

Abstract

A circuit breaker contact assembly includes a line conductor having a folded back fixed contact end, a fixed contact mounted on the contact end, and a movable contact arm having an inner edge and first and second ends. A movable contact is mounted on the first end. The movable contact arm is pivotable about the second end between a closed position in which the inner edge extends adjacent the contact end with the movable contact in contact with the fixed contact to form a reverse current loop, and an open position in which the movable contact is pivoted away from the fixed contact. The contact arm includes a first inner longitudinal member extending along the inner edge and a second outer longitudinal member. The first inner longitudinal member has a higher electrical conductivity than the second outer longitudinal member, which has a higher shear strength and a lower specific density.

1. A contact assembly for a circuit breaker, said contact assembly comprising:
 a line conductor having a folded back fixed contact end; 
 a fixed contact mounted on the fixed contact end of the line conductor; 
 a movable contact; and 
 a movable contact arm having an inner edge, an outer edge, a first end and a second end, the movable contact mounted on the first end, the movable contact arm being pivotable about the second end between a closed position in which the inner edge extends adjacent the folded back fixed contact end of the line conductor with the movable contact in contact with the fixed contact to form a reverse current loop and an open position in which the movable contact is pivoted away from the fixed contact, the movable contact arm having a cross section that is narrower in width toward the outer edge opposite the inner edge than at the inner edge, 
 wherein the movable contact arm comprises a first inner longitudinal member and a second outer longitudinal member, the first inner longitudinal member having a higher electrical conductivity than the second outer longitudinal member and the second outer longitudinal member having a higher shear strength than the first inner longitudinal member. 
 
   
   
     2. The contact assembly of  claim 1  wherein the second outer longitudinal member has side edges that taper inward toward the outer edge. 
   
   
     3. The contact assembly of  claim 1  wherein the first inner longitudinal member is made of copper. 
   
   
     4. The contact assembly of  claim 3  wherein the second outer longitudinal member is selected from a group comprising aluminum and an aluminum alloy. 
   
   
     5. The contact assembly of  claim 3  wherein at least one of the first inner longitudinal member and the second outer longitudinal member has a cross section including a height and a width, said height being greater than said width.